Halophilic nematodes live in America’s Dead Sea

Extremophiles can reveal the origins of life on Earth and the possibility of life elsewhere. Most identified extremophiles are single-cell microbes, leaving gaps in our knowledge concerning the origins and habitable limits of multicellular organisms. Here, we report the recovery of roundworms (Phylum Nematoda) from the Great Salt Lake (GSL), UT, a hypersaline lake referred to as “America’s Dead Sea”. Nematodes were found primarily in microbialites, benthic organosedimentary structures once abundant on early Earth. 16S sequencing of individual nematodes revealed a diverse bacterial community distinct from its surrounding habitat. Phylogenetic divergence compared to Owens Lake, another terminal lake in the Great Basin, suggests that GSL nematodes represent multiple previously undescribed species. These findings update our understanding of halophile ecosystems and the habitable limit of animals. One-Sentence Summary We report the discovery of novel halophilic nematodes in microbialites of the Great Salt Lake, UT. ### Competing Interest Statement The authors have declared no competing interest.